1. Field of the Invention
The invention relates to a vehicle with hybrid drive, in which the driving power provided by an internal combustion engine or an electric motor is fed to the drive train via a transmission with a transmission input shaft and a transmission output shaft. The internal combustion engine and the electric motor are connectable to each other via a coupling. The electric motor is directly connected to the transmission. The vehicle also includes an electric energy storage device for providing power to the electric motor that is chargeable by the internal combustion engine. A process for operating a hybrid vehicle with a satellite-controlled navigation system is also disclosed.
2. Description of the Related Art
A hybrid vehicle of the aforementioned type is known, for example, from references DE 43 23 601 A1 and DE 29 43 554. The reference DE 29 43 554 discloses a hybrid vehicle started by the electric motor alone. The internal combustion engine (ICE) of this prior art vehicle is started only after a minimum speed is attained using the stored kinetic energy of rotating masses between two separating couplings. After being started, the ICE is accelerated very quickly to the speed of the electric motor. During uphill and/or accelerating travel, the electric motor is operated with the ICE, in a known manner, as a simultaneously acting driving engine, and during downhill and/or deceleration phases, the electric motor is operated as a generator to feed an energy storage device.
Another prior art reference DE 44 22 636 A1 discloses a process for the automatic control of an ICE in hybrid vehicles. This prior art control process discloses using one of four operating modes of the ICE depending on the driving state of the vehicle. In a first operating mode, power is provided by the ICE only when a preestablished minimum value of an operating parameter proportional to the vehicle speed is reached. In a second operating mode, power is provided by the ICE when the total power demanded exceeds a short-term power limit. In a third operating mode, power is provided by the ICE delayed by a preestablished time period when the total power demanded exceeds a long-term power limit and falls below a short-term power limit. In a fourth operating mode, when the charge level of the electric energy storage device has dropped to a lower limit, power is provided by the ICE until an upper limit of the charge level is again attained. The ICE is turned on when the power available from the electric motor is no longer sufficient. The long-term power limit is defined in the aforementioned publication as the power that can be delivered permanently by the electric energy storage device.
Yet another control device for a hybrid vehicle is disclosed in prior art reference DE 195 23 985 A1. In this control device, power produced by the driving engine is applied via a generator inverter to an engine/generator, so that the engine/generator drives the ICE to apply a braking force to the latter. In this way, power produced during regenerative braking that cannot be absorbed by a saturated battery (such as during downhill travel) is used to support the braking of the vehicle.
All known hybrid vehicles require a large structural space for the driving unit because the ICE and the electric motor are connected one behind the other with a coupling between them and the transmission is connected to the electric motor. The additional space requirement created by the parallel hybrid drive must be as small as possible. For installation in existing vehicles having a conventional drive unit, a maximum lengthening of 30 mm, compared with the conventional driving unit, is permissible. Otherwise, the structure of the vehicle would have to be modified. Given the low production number of the hybrid vehicles, any required structural modification would lead to a considerably greater expense. Therefore a problem of the prior art hybrid vehicles is to minimize the additional space requirement. In addition, the use of each of the ICE and electric motor must be properly selected to produce the greatest savings in fuel consumption.